1.1 KiB
1.1 KiB
N-Queens
What is the N-Queens Problem?
Imagine you have a chessboard and some queens (the most powerful pieces in chess). The N-Queens problem is like a puzzle where you need to place N queens on an N×N chessboard so that none of them can attack each other.
What's a Queen in Chess?
A queen is the strongest piece in chess. She can move:
- Horizontally (left and right)
- Vertically (up and down)
- Diagonally (in any diagonal direction)
She can move as many squares as she wants in these directions!
The Challenge
Let's say we want to solve the 4-Queens problem (N=4):
- We have a 4×4 chessboard (16 squares total)
- We need to place 4 queens
- NO queen can attack any other queen
Example: What Does "Attack" Mean?
If we put a queen at position (0,0) - that's the top-left corner - she can attack:
Q . . . ← Queen here attacks all positions marked with X
X . . .
X . . .
X . . .
Q X X X ← Queen attacks horizontally
. . . .
. . . .
. . . .
Q . . . ← Queen attacks diagonally
. X . .
. . X .
. . . X
So we can't put any other queen in any of those X positions!